In case you didn't spot it yet: Opera uploaded a new developer release (25.0.1605.0) yesterday, but Windows only this time without any changelog or blog post. It's not auto-updating either.
You can get it here

We have recently begun experimenting with a fresh, new look for Speed Dial.

The right time to switch Mac to 64-bit:
We held off on switching Mac to 64-bit until the benefits outweighed the downsides. Today, we think we have reached that milestone. Some of the changes that allowed us to make the switch include:

New 64-bit only API possibilities, with the upcoming release of Yosemite